Hi, so I have a little Proxmox box with two VMs: VM1 and VM2 which is a clone of VM1. I change the mac of VM2 to avoid conflict and I reset the machine ID of VM1. I then have a seperate pfSense machine machine that that acts as router, firewall and DHCP server. Proxmox is on the 192.168.20.1/24 domain. In the DHCP server, Proxmox get IP 192.168.20.8 explicitly assigned. All good to this point. I've set VMs on pfSense to get the 192.168.20.9X addresses assigned. VM1 gets 192.168.20.91 assigned, while VM2 should be getting 192.168.20.92.
But this is what actually happens:
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VM1 gets 192.168.20.106 assigned, despite telling pfSense to assign it 192.168.20.91. This happens even with VM2 shutdown. The DHCP Lease table is showing 91 up and running and does not list 106. Yet, the ARP table shows 106 assigned and no 91 assigned. This is even with me deleting the 106 entry from the ARP table several times and rebooting both the VM and the Proxmox server.
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The VM is definately getting 106 assigned as I can log into it with 106 IP but 91 doesn't respond (no route to host).
Is this something to do with the bridge configuration on Proxmox? Iv'e added a screenshot of what I see. It doesn't seem to be that complicated to setup a bridge?
I can't get my head around this so tips are welcome.
EDIT: I've just run 'sudo ip' on the VM and i see the ens18 interface with the MAC I assigned to it and the 106 IP assigned to this interface. There are then seven of 'vethXXX' interfaces. Not sure what these are. There are also four 'brXXXX' interfaces, one 'loXXXX' interface and one 'docker0' interface, the latter probably used by the docker subsystem running on the VM. I imagine the 'brXXXX' interfaces are the docker containers themselves (I think I have four running). But what are the 'vethXXXX' interfaces? Sounds like its something to do with "virtual interface". Why so many and what is creating these?
Is there a reason you sre using dhcp instead of assigning ips manually?
Dhcp is great if you don't care about stuff, in my experiece as soon as you start caring you should do it manually
Wrong. It’s 2026. You should be setting static dhcp entries and using dhcp to ensure static IPs, not avoiding dhcp. Using manually assigned static IPs just means you’ve built a fragile unique snowflake.
Dhcp and ensuring it works is someting I don't care about. I tell the kernel wich packets it should be interested in and how to sign itself and that will be it thank you very much.
I configure static routes and have all my machines and network segments neatly arranged in my database. I setup a new machine I know exactly what address it should have,it goes up and until it has a problem it will keep the address it was installed with.
Its 2026 I work like that, you can have your opinions I have mine. The difference is that I depend on one less thing that I don't care about, so I have more profit margin.
Very old school; yes you can certainly do all of that and track all of that yourself. We all used to do it that way……But it’s 2026….just as you’d use a real editor rather than edlin, or password managers rather than text files, the new ways ARE better, easier and more consistent. Making sure dhcp works is one of the modern (honestly not that modern) basics that make sure your network is set up properly and isn’t hiding some misconfiguration gremlins that only work because of some static ip and route workaround you implemented years ago and worked “until now”.
I don't know what I'm doing, please explain.
DHCP can be set to specifically assign the same IP to specific devices, reserving them and ensuring that no other systems will use the same IP accidentally. So your servers will consistently get that same IP address assigned to them every time, no worry about the ip address changing unexpectedly.